The Joint Council of Interns and Residents sued the Los Angeles County Board of Supervisors to halt the eventual placement of all physicians assigned to the county's largest hospital on the payroll of USC's School of Medicine. The Superior Court suit, which will be considered in two weeks, alleges that the board-approved action to transfer the interns and residents violates a 1978 county Charter amendment. That voter-approved provision requires that any time government contracts out public services--in this case physician care--to the private sector, it must first show that such a move would not cost taxpayers additional money. About 850 interns and residents work at County-USC Medical Center as county employees. Under the disputed board-approved plan, about 215 incoming replacement physicians would become USC School of Medicine employees on June 1.